Be aware: sort order is source (e.g. folder/collection) specific, so if you change it in one place, it doesn't change it in other places. That's probably what's happening - i.e. you changed it one place, then switched folder / collection, and sort order seemed to have inadvertently changed. Could that be it?

No. It is as I wrote... I know how LR works. I simple want to be able to lock the sort order. For every individual folder/collection. As said: it is changed too easily: one accidental move of the pen and I have a user order instead of whatever it was.